This invention relates to machines for forming crop material into cylindrical bales and more particularly to machines in which the bales are formed snowball-like while being rolled along the ground. Such machines are inherently simpler and lower in cost than machines which maintain the material clear of the ground while the bale is being formed. However, even recent machines of this type produce poorly formed bales and suffer substantial crop loss due to imperfect action of the pickup and bale propelling means. In these machines, constant contact between the pickup means and the growing bale tends to increase crop losses, reduce bale density and may retard the propulsion of the bale.